The invention relates to a coupling that couples a pulled implement or trailer with a drawbar to a tractor. The tractor has a three-point linkage device with two power driven, height-adjustable lower steering arms. At least one arm is laterally pivotable by a power drive. A first coupling element is coupled with a second coupling element which is arranged on the drawbar.
Nowadays, in single-axle or multi-axle trailers the so-called lower linkage is used more and more on tractors. In this linkage a tow-hook, a tie-bolt or a ball is rigidly mounted on the rear of a tractor as a first coupling element. The drawbar of the trailer includes a corresponding second coupling element, which has a trailer coupling ring or a ball socket. During the coupling process, the first coupling element, which is arranged on the tractor, is difficult to see. Because of this reason tow-hook couplings are used. The tow hook coupling includes a tow-bar that carries the first coupling element in the form of a tow-hook, which has a tow-bar pivotable in the horizontal plane, as well as in a vertical plane. The lifting movement is produced by the lifting arms of the power lift. The tow-bar is telescopic so that it is adjustable lengthwise. In order to couple, the tow-bar can be elongated so that the driver of the tractor can determine, from the driver""s seat, the approach of the tow-hook to the trailer coupling ring on the drawbar of the to be attached trailer. By actuating the power lift, the tow-hook is lifted and is inserted into the trailer coupling ring of the drawbar. By reversing the coupling process, the tractor tow-bar can be returned to its original length and locked to the rear of the tractor. Such a tow-hook coupling is described in DE-AS 1249707.
U.S. Pat. No. 6,089,328 A discloses a tractor linkage device with two lower steering arms arranged on the rear of the tractor and laterally distanced from each other. The arms are height-adjustable and additionally can be pivoted towards or away from each other. A power lift is provided for the height adjustment. A hydraulic cylinder arranged on each lower steering arm laterally pivots each arm. The length of the hydraulic cylinders can be controlled automatically by a control system.
FR 2 803 560 A1 describes a coupling means for an implement or a trailer with a drawbar to connect to a tractor. The coupling has rocker arms mounted on the drawbar and includes two arms, each provided with a hook, respectively, on its free ends. The hooks engage a lift link draw bar mounted on the lower steering arms. The drawbar is lifted by the lower steering arms. By reversing the tractor, the trailer coupling ring on the drawbar is brought into a corresponding position on a hook on the rear of the tractor. After lowering the drawbar, a connection is achieved between the two. The above described arrangement necessitates, that the driver of the tractor precisely determines when a position is achieved, which enables a coupling of the trailer coupling ring to the tow-hook mounted on the tractor. This is practically impossible from the driver""s seat, because of the arrangement on the rear of the tractor.
An object of the invention is to provide a coupling to couple a pulled implement or trailer with a drawbar to a tractor. The coupling facilitates, by using the three-point linkage device of the tractor, the approach connection between a second coupling element, which is mounted on the drawbar of the implement or of the trailer, and a first coupling element, provided on the rear of the tractor. The coupling has a simple structure.
The coupling couples a pulled implement or trailer with a drawbar to a tractor having a three-point linkage device with two power driven, height-adjustable lower steering arms. At least one arm is laterally pivotable by a power drive. A first coupling element connects with a second coupling element which is arranged on the drawbar. The coupling includes a bar with two ends. A connection element is at both ends of the bar to connect to the lower steering arms of the tractor. A guiding mechanism which serves to orientate the drawbar, enables a relative movement of the draw bar in the longitudinal direction. A travel-limiting mechanism is mountable on the drawbar and limits the relative travel of the drawbar in the longitudinal direction.
Furthermore, the coupling couples a pulled implement or trailer with a drawbar to a tractor having a three-point linkage device with two power driven, height-adjustable lower steering arms. At least one arm is laterally pivotable by a power drive. A first coupling element is connected to a second coupling element that is arranged on the drawbar. The coupling includes a bar with two ends. A connection element is at both ends of the bar to connect to the lower steering arms of the tractor. A guiding mechanism which serves to orientate the drawbar, enables a relative movement of the draw bar in the longitudinal direction. An indicating mechanism is mountable on the drawbar. The indicating mechanism indicates the relative travel of the drawbar to the bar, necessary for coupling the first coupling element to the second coupling element.
An advantage of these couplings is that only one bar received in the coupling hooks of the lower steering arms is necessary. The guiding mechanism for guiding the drawbar, is mounted on the bar. The drawbar rests on the bar and thus can be lifted and lowered by the power lift. The guiding mechanism enables a longitudinal adjustment and relative movement in the longitudinal direction of the drawbar between the drawbar and the bar. Thus, the second coupling element approaches the first coupling element. If this second coupling element is in the range of the first coupling element, which is mounted on the rear of the tractor, the travel-limiting mechanism on the drawbar abut the bar. Accordingly, the lower steering arms can be lowered, whereby the two coupling elements are brought into engagement. The coupling elements described in the state of the art, e.g. tow-hooks, tie-bolts or ball couplings can be used as coupling elements. If a lateral orientation of the second coupling element to the first coupling element is necessary, as the longitudinal axis of the drawbar does not correspond to the longitudinal axis of the tractor, the hydraulically operated lateral strut can be actuated. Here the lower steering arms are laterally pivoted and the second coupling element is aligned with the first coupling element mounted on the tractor.
An indicating mechanism can be used instead of an abutment to limit the relative movement of the drawbar in the longitudinal direction in relation to the bar. The abutment is mountable on the drawbar and abuts the bar. The indicating mechanism to the bar can be seen by the driver of the tractor when he sits on the seat of the tractor. From the position towards the bar, it can be determined whether the second coupling element, which is arranged on the drawbar, has approached the first coupling element in the correct way.
Preferably, the travel-limiting mechanism which is attachable on the drawbar, is provided in form of an abutment, which interacts with the bar. The indicating mechanism can be a marking mountable on the drawbar.
As an improvement of both alternatives according to the invention, the guiding mechanism is represented by two guiding pins. The pins are mountable on the bar distanced from each other. Accordingly, bores are provided in the bar to enable detachable attachment of the guiding pins.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.